The application relates to compositions comprising di-fatty-alkyl or -alkenyl polyalkylamines of the general formula (I) or (II), to a process for their preparation which involves a cyanoethylation step and a hydrogenation step, and their use as demulsifiers for oil-in-water emulsions, corrosion inhibitor, fuel additive, anti-scaling agent, asphalt additive, enhanced oil recovery agent for oil-wells, cutting-oil additive, and anti-static agent. The product show good performance combined with a favourable viscosity profile.